The present invention relates to elastic seals for use in ball, roller and other antifriction bearings, and to antifriction bearings which utilize such seals.
It is already known to construct an antifriction ball or roller bearing in such a way that a portion of one of the races extends axially beyond the other race and the axially extending portion of the one race carries an elastic seal with a lip which is in sealing and sliding contact with the adjacent end face of the other race. The purpose of the lip and of that portion of the seal which is secured to (e.g., embedded in) the portion of the one race is to reduce the likelihood of penetration of foreign matter into the gap which is provided between the two races and extends axially toward the space for the rolling elements of the antifriction bearing. In many instances, the portion of the one race is formed with a circumferentially complete groove for a relatively thick and stable washer-like supporting portion of the seal.
A seal of the above outlined character ensures adequate prevention of penetration of foreign matter into the gap between the two races, not only because the seal is anchored in one of the races and its lip bears against the adjacent end face of the other race but also because the lip allows for the accumulation of a ring of lubricating material therealong whereby the thus accumulated lubricating material further reduces the likelihood of penetration of foreign matter into the space for the rolling elements. The just described seals are particularly effective when the axis of the assembled antifriction bearing is vertical and the bearing is adequately lubricated; the lip and the developing ring of lubricating material then satisfactorily shield the rolling elements from dust, moisture and/or other foreign matter which could adversely affect the useful life of the bearing. However, it has been ascertained that the shielding action of the aforedescribed conventional seals is much less satisfactory when the axis of the bearing is horizontal or substantially horizontal and the bearing is not lubricated at sufficiently frequent intervals. In fact, a bearing which is adequately lubricated is still likely to permit penetration of moisture and/or other undesirable foreign matter (irrespective of the inclination of its axis) if it is cleaned with one or more jets of water at an elevated pressure or with one or more jets of steam. Moisture which penetrates into the space for the rolling elements of the bearing is likely to cause considerable damage or, at the very least, reduce the useful life of the bearing.
Attempts to overcome the drawbacks of the above described conventional bearings and their seals include the provision of several additional seals in the form of rings having a substantially V-shaped cross-sectional outline and being inserted into the gap between the two races so that their legs extend into grooves machined therefor in those surfaces of the races which bound the groove. The machining of grooves into those surfaces of the races which flank the gap contributes to the cost of such bearings. Moreover, the grooves for the V-shaped sealing rings in the inner and outer races of the bearing cannot be placed into immediate proximity of each other so that the utilization of such additional sealing rings necessitates an increase of the bulk and weight of the bearing, especially an increase in the axial dimensions of the races. Therefore, bearings with several V-shaped sealing rings are used only for special purposes and have failed to gain widespread acceptance in the industry. The initial cost of such bearings is much higher than that of bearings with single seals, and the cost of replacing V-shaped sealing rings is high because the rings cannot be reached without at least partial dismantling of the bearings.